Thermal insulators for metal door and window frames



July 25, 1967 A. P. MCEVOY 3,332,184

THERMAL INSULATORS FOR METAL DOOR AND WINDOW FRAMES Filed July 16, 1965 2 Sheets-Sheet 1 I EL 3 I /6 FIG. 6

' FIG! E2 L NVENT OR 1 Alfred P. M Evoy FIG. 7 9

ATTORNEYS THERMAL INSULATORS FOR METAL DOOR AND WINDOW FRAMES Filed July 16, 1965 2 Sheets-s 2 INVENTOR Alfred 9 MC Evoy FIG. 4

ATTORNEYS United States Patent 3,332,184 THERMAL INSULATORS FOR METAL DOOR AND WINDOW FRAMES Alfred P. McEvoy, Dallas, Tex., assignor to General Aluminum Corporation, Carrollton, Tex., a corporation of Texas Filed July 16, 1965, Ser. No. 472,442 12 Claims. (Cl. 522il4) This invention relates to new and useful improvements in thermal insulators for the metal frames of doors and windows.

As is well known, metal door and window frames are highly desirable and in extensive, Widespread use due to their durability and strength and are in greater demand when constructed of aluminum or other nonferrous metal requiring no finish and minimum maintenance. Aluminum is most popular because of its economy of manufacture, handling and transportation due to aluminum being relatively inexpensive, capable of being formed by extrusion and of light weight. Since metal has poor insulating characteristics, moisture condenses on metal frames, whenever there is sufficient differential between the indoor and outdoor or other opposed temperatures and humidity to which the frames are exposed, and causes the accumulation of moisture which is highly detrimental to the interior surfaces of the walls in which said frames are mounted as well as to draperies and, especially, to the interior casings, trims or portions of said walls normally in engagement with said frames.

Since it is virtually impossible to prevent the condensation of moisture on the interior portion or side of a metal door and window frame exposed to opposed temperature and humidity conditions, it is the principal object of this invention to provide a barrier for preventing the condensed moisture from being conducted to the interior casing, trim or immediately surrounding portion of the wall in which the frame is mounted. This highly desirable objective is attained by providing a thermal insulator having a retainer or retainers of nonmetallic material for mounting on the interior side of a metal door or window frame and in minimum contact therewith to insulate and space the frame from contact with any portion of the interior side of the wall in which said frame is mounted. In order to provide minimum contact and heat transfer between the frame and the interior side of the wall, the retainer or retainers are engaged only with a portion or portions of said frame whichare not exposed directly to indoor atmospheric or temperature and humidity conditions with suitable insulating means being confined between said retainer or retainers and the portion or portions of said frame which are exposed directly to indoor atmospheric conditions whereby the portion or portions of said frame upon which moisture condenses are spaced sufficiently from the interior side of the wall to prevent the condensed moisture from being conducted to said interior side of said wall. Since the retainer adapts itself to the formation of a dead air insulating space for coacting with the insulating means, the latter may be of minimum area to conserve cost and facilitate flexing of said retainer into engagement with the frame whereby said retainer may be adapted to be mounted on substantially any metal frame capable of being mounted in a door or window opening.

In essence, this invention consists of the idea of economically, thermally insulating any metal door or window frame from the interior side or inside portion of a wall in which the frame is mounted, in such manner, that any moisture condensation on said frame is prevented from being conducted to said interior wall portion or side so as to prevent deterioration of the latter. It is essential that the insulator be as unobtrusive as possible, from the 3,332,184 Patented July 25, 1967 aesthetic viewpoint, without detracting from its efiiciency and without making its mounting on a door or window frame and the installation of the latter more difficult. The insulation of the frame from the interior wall portion or side includes the spacing of said frame from said wall portion or side as well as the confinement of thermal insulating means by the retainer between said frame and retainer to assist the dead air insulation provided by said spacing as well as to minimize heat transfer between said retainer and frame. The interior portion or side of the frame is flanged to permit gripping engagement of the retainer therewith and may consist of a single or unitary flange or a pair of flanges or flange portions projecting laterally from said frame.

A construction designed to carry out the invention will be hereinafter described, together with other features of the invention.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings, wherein examples of the invention are shown, and wherein:

FIG. 1 is an elevational view of a thermal insulator constructed in accordance with this invention and mounted on a metal window frame installed in a building opening, the window being removed for clarity of illustration,

FIG. 2 is an enlarged, transverse, vertical, sectional view, taken on the line 22 of FIG. 1, showing the insulator mounted on the head of the frame,

FIG. 3 is a view, similar to FIG. 2, taken on the line 3-3 of FIG. 1, showing the insulator mounted on the sill of the frame,

FIG. 4 is an enlarged, broken, horizontal, cross-sectional view, taken on the line 44 of FIG. 1, showing, the insulator mounted on one of the jambs of the frame, and

FIGS. 5, 6 and 7 are views, similar to FIGS. 2, 3 and 4, respectively, on a larger scale and showing only portions of the head, sill and jamb of the frame.

In the drawings, the numeral 10 designates a thermal insulator embodying the principles of the invention and mounted on the interior side of a window frame 11 of aluminum or other suitable metal. As shown most clearly in FIGS. 2-4, the frame 11 includes a conventional head or top framemember 12, a sill or bottom frame member 13 and a pair of jambs or side frame members 14 and is adapted to be installed in an opening 15 of a building wall in the usual recessed manner. Although subject to variation, the building wall is illustrated as being of the veneer type and formed of spaced, inner and outer walls 16 and 17 having a header 18 and a lintel 19, respectively, overlying the opening 15 (FIGS. 2 and 5). The inner wall 16 includes a sill member 20 underlying the building opening (FIGS. 3 and 6) and studs or jamb members 21 forming the sides of said opening (FIGS. 4 and 7) as well as exterior furring 22 and an interior surface 23 of gypsum board or other suitable material. As shown, the gypsum board may extend into the opening 15 in overlying relation to the head 18, sill member 20 and studs 21 to provide an interior trim, casing or head, sill and jamb liner 24; however, the trim may be formed of wood, metal or suitable material and may overlie the margins of said gypsum board adjacent the opening 15 as well as said header, sill member and studs.

The members (head 12, sill 13 and jambs 14) of the frame 11 are angular in cross-section, being suitably connected to one another, and have external, laterally-projecting portions 25 for overlying the furring 22 and securing said frame to the inner wall 16 in addition to exterior marginal portions 26, which may be angular, for sealing engagement with the outer wall 17 within the opening 15. Although the illustrated frame is adapted to receive a single hung window (not shown), it is pointed out that the cross-sectional contours of its members vary in accordance with the type of window or other closure, such as a door, mounted in said frame and the wall construction and that the window may be of the stationary or picture window type and/ or may have a door hung or slidably mounted therein.

The frame 11, per se, forms no part of the present invention which is concerned only with thermally insulating the interior portion or side of said frame exposed to the interior of the building so as to prevent the conduction of moisture resulting from condensation on said frame interior portion or side to the interior Surface of the inner wall 16 and, particularly, the trim 24 which normally engages said frame. Since the metal frame is exposed to outdoor weather conditions as well as to in door temperature and humidity conditions and has high thermal conductivity, condensation occurs at the interior side of said frame whenever the indoor temperature and humidity exceeds the outdoor temperature and humidity by a critical amount and the resulting moisture is transmitted to the interior trim. Manifestly, repeated condensation and formation of moisture on the interior side of the frame over a period of time causes deterioration of the trim 24 as well as its finish and spreads to the adjacent portion of the interior surface of the inner wall as well as to draperies (not shown). This deterioration is most pronounced at the sill or stool area of the opening 15. Therefore, it is essential to prevent any portion of the frame 11 from engaging the interior surface of the inner wall 16 and, particularly, the trim 24. As will be apparent, the thermal insulator is adapted to achieve this highly desirable result.

As shown in FIGS. 2 and 5, a pair of upright, parallel flanges 27 and 28 are coextensive with and project perpendicularly from the interior margin of the head or frame member 12 in opposite directions whereby the flange 27 extends later-ally inward and the flange 28 extends laterally outward of said head or frame member. Usually but not necessarily, the frame flanges are offset relative to each other to provide an outwardly-facing shoulder 29 for engaging the exposed surface of the trim 24 when the outer frame flange 28 engages the outer margin thereof. Since this contact is undesirable due to the moisture caused by condensation, the flanges could be alined insofar as this invention is concerned whereby the interior portions of the frame member would be T-shaped in cross section (FIGS. 4 and 7) and said flanges would form coacting portions of a single flange extending laterally from both sides of said frame member.

Referring to FIGS. 3 and 6, the sill or frame member 13 has offset, inwardly and outwardly directed, lateral flanges 30 and 31 at its interior margin which correspond to the lateral flanges 27 and 28 of the head or frame member 12. An outwardly facing shoulder 32 is formed by the offsetting of the frame flanges 30 and 31 for overlying a sill or the sill portion of the trim 24 which normally engages the outer frame flange 31. Since the sills of most frames are inclined downwardly and outwardly, as shown, the outer frame flange is ordinarily of much greater width than the inner frame flange 30. As pointed out in connection with the head or frame flanges 27 and 28, the flanges 30 and 31 may be in alinement to form portions of a single flange.

As shown in FIGS. 4 and 7, similar lateral flanges or flange portions 33 and 34 project inwardly and outwardly from the interior margin of each jamb or frame member 14 and usually are alined with the inner frame flange 33 being of greater width than the outer frame flange 34. A rib 35 may extend longitudinally between the frame flanges or medially of the flange portions for engaging the exposed surface of the trim 24 when the outer frame flange 34 engages the outer margin thereof. As noted in connection with the offsetting of the head and sill or frame flanges, the rig is unnecessary to this invention.

Even though not identical, the frame flanges 27-28, 30- 31 and 3334 coact to provide a perimetrical flange for the frame 11.

For mounting on the flanges 27 and 28 of the head or frame member 12, the thermal insulator 10 includes an elongate retainer 36 adapted to extend throughout the length of said flanges and formed of suitable nonmetallic material, such as vinyl or other suitable synthetic resin, having limited thermal conductivity and limited rigidity so as to be capable of undergoing flexing (FIG. 5). The retainer 36 is of generally channel or U-shape in crosssection and comprises a pair of longitudinal parallel, spaced flanges 37 and 38 connected by a coextensive, preferably perpendicular web 39 of a width greater than the combined width of the frame flanges. A pair of closed-spaced, coextensive ribs 40 projects laterally inward from the outer edge portion of the outer flange 38 of the retainer, toward its other or inner flange 37 and in spaced relation to its web 39, for gripping engagement with the outer marginal portion of the outer frame flange 28 so as to confine said frame flange therebetween. Preferably, the distance between the bases of the ribs 40 is slightly greater than the thickness of the frame flange and the outermost rib is inclined inwardly toward the innermost rib to permit said ribs to be snapped into confining engagement with said frame flange.

A longitudinal leg or lip 41 extends laterally inward from the outer margin of the other or inner flange 37 of the retainer 36 toward the outer retainer flange 38 in spaced relation to the web 39 and inner frame flange 27 and, as shown, the lip may be parallel to said web. In coaction with the inner retainer flange the lip 41 is adapted to engage and confine a strip 42 of suitable thermal insulating material which is coextensive with the retainer and which is of U-shape in cross-section so as to have a longitudinal channel or groove 43 for gripping engagement with the outer portion of the inner frame flange 27. The insulating strip may be formed of expanded polystyrene or other material having low thermal conductivity and high flexibility. Since the retainer web is of a width greater than the combined width of the frame flanges, the retainer flange 37 is spaced from the frame flange 27 to accommodate a portion of the strip 42 therebetween. This essential spacing may be obtained by inclining one or both of the retainer flanges outwardly relative to the web 39 or by outward offsetting of said retainer flanges whereby said web may be of a width equal to or less than the combined width of the frame flanges.

A longitudinal bead or rib 44 may project inwardly from the intermediate portion of the web 39 so as to engage the outer face of the insulating strip and coact with the inner flange 37 of the retainer 36 and its lip 41 to confine said strip against displacement. Although the retainer web may engage the strip 42, as will be apparent, it is desirable to provide a relatively narrow, longitudinal bead 45 on said web between the inner flange 37 and rib 44 for engaging said strip to provide a secondary dead air insulating space 46 between the major portions of the adjacent faces of said strip and web. A primary dead air insulating space 47, of greater area, is formed between the web 39 and the outer frame flange 28 as well as the inner portion of the inner frame flange 27, due to said web being spaced from the frame flanges by the gripping engagement of the ribs 40 and insulating strip with said frame flanges, said gripping engagement detachably securing the retainer to said frame flanges. Due to the strip 42 being of less area than the interior of the retainer 36 and the flexibility of said strip, it does not interfere with the flexing of said retainer into engagement with the frame flanges. Also, the insulating strip is not required between the outer frame flange 28, which is not exposed directly to indoor atmospheric conditions, and the outer portion of the retainer web, which engages the outer margin of the interior trim 24, since the insulation provided by the dead air space 47 is adequate.

As shown most clearly in FIG. 6, the portion of the thermal insulator adapted to be mounted on the flanges 30 and 31 of the sill or frame member 13 includes a retainer 48 which is very similar to the retainer 36 and which has similar inner and outer flanges 49 and 50 connected by a similar web 51. Substantially identical ribs 52 are formed on the outer edge portion of the outer flange 50 of the retainer 48 for gripping and confining the outer marginal portion of the outer frame flange 50 therebetween whereby a dead air insulating space 53, similar to the dead air insulating space 47, is provided by the spaced relationship of the retainer web 51 and said frame flange. The other or inner retainer flange 49 has a substantially identical leg or lip 54 on its outer margin and in spaced relation to the sill or frame member 13 for coacting with said retainer flange to engage and confine a substantially identical thermal insulating strip 55 on the inner frame flange 49 which, as shown, may be completely engaged in the longitudinal channel or groove 56 of the strip whereby strip confining means, similar to the rib 44 of retainer web 39, is not required.

In addition to engaging the retainer flange 49 and its lip 54, as shown, the strip 55 also may engage the retainer web or may be spaced from said web, in the same manner as the web 39 of the retainer 36 is spaced from the insulating strip 42, to provide an additional or secondary dead air insulating space (FIG. 5). Due to its appreciable width, the web 51 may be reinforced by longitudinal beads 57 which project inwardly of the intermediate portion of said web intothe dead air insulating space 53 (FIG. 6). It is noted that the rib 44 and bead 45 reinforce the web 39 of the retainer 36 as well as coact with the strip 42 and that said bead may be omitted or disposed in the dead air insulating space 47 to permit said web to engage said strip upon increasing the transverse width of the latter or reducing the width of the inner retainer flange 37 and changing the relationship of the frame flanges 27 and 28 (FIG. 5). The outer portion of the retainer web 51 engages the outer margin of the return or trim 24 in the same manner as the retainer web 39, while the outer retainer flange 50 rests on the sill member 20.

The portion of the thermal insulator 10 adapted to be mounted on the flanges 33 and 34 of each jamb or frame member 14 includes a retainer 58 similar to the retainers 36 and 48 and having similar inner and outer flanges 59 and 60 as well as a similar web 61 (FIG. 7). Ribs 62, similar to the ribs 40 and 52 but of greater width, project inwardly of the outer edge portion of the outer flange 60 of the retainer 58 to grippingly engage and confine the outer portion of the outer frame flange 34 therebetween in spaced relation to the web 61 to provide a dead air insulating space 63 between said frame flange and web. The other or inner retainer flange 59 has a relatively narrow, longitudinal rib 64, in place of the relatively wide legs or lips 41 and 54 of the retainers 36 and 48, projecting inwardly from its outer edge portion toward and in spaced relation to the inner frame flange 33 for coacting with said retainer flange to confine a strip 65, of the same thermal insulating material as the strips 42 and 55, between the retainer web and said frame flange. The insulating strip 65, which extends throughout the length of the retainer 58, is rectangular in cross-section and of greater width than thickness since the frame flanges 33 and 34 are in alinement instead of being offset relative to each other like the flanges of the head and sill or other frame members 12 and 13.

It is noted, however, that the strip 65 could be substantially identical to the insulating strips 42 and 55 for gripping engagement on the outer portion of the inner frame flange 33, that the widths of the inner retainer flange 59 and its rib 64 could be increased to confine the modified strip in the same manner as the inner flanges 37 and 49 and lips 41 and 54 of the retainers 36 and 48, respectively, and that said strip 65 could be spaced from the retainer Web 61 in the same manner as said strip 42 (FIGS. 5 and 6). Also, the strips 42 and 55 could be rectangular instead of U-shaped in cross-section and could be confined in the same manner as the strip 65 even if the frame flanges 27 and 28 and frame flanges 30 and 31 are not alined. A head or rib 66, similar to the rib 44, projects inwardly from the intermediate portion of the web 61 so as to engage the inner face of the strip 65 for coacting with' the inner flange 59 of the retainer 58 and its rib 64 to confine said strip against displacement (FIG. 7). When the jamb or frame member 14 is provided with the rib 35, it may be utilized to engage the inner face of the insulating strip and assist in confining said strip. Although the upper and lower ends of the jamb retainers 58 and insulating strips 65 could engage the inner flanges 37 and 49 of the head and sill retainers 36 and 48, it is preferable to remove portions of said flanges 37 and 49 to provide a closer fit between said retainers and strips. Also, a substantially continuous, perimetrical, thermal insulator may be formed by the coaction of the strips 42, 55 and 75 as well as by the dead air insulating spaces 46, 47, 53 and 63'.

As pointed out hereinbefore, each pair of the inner and outer frame flanges 27-28, 30 31 and 33-34 may be alined with each other and with the flanges of the other pairs of said flanges whereby the interior portion .or side of the frame is T-shaped in cross-section and each pair of flanges form the lateral projecting portions of a single flange. Manifestly, the configuration of the retainers and insulating strip must conform to the contours of the frame flanges for coaction therewith and said contours vary in accordance with the construction of the wall in which the opening 15 is formed and, primarily, with the type of door or window mounted in the frame 11. Each of the retainers spaces the interior portion or side of the frame from contact with the interior surface of the inner wall 16, and, particularly, the interior trim 24 which normally engages said frame. This spacing provides a dead air insulating space 47, 53 or 63 between the frame and the trim which communicates only with the usual dead air space between the inner and outer walls 16 and 17.

Although the web of each retainer engages the trim, the minimum contact of the retainer with the frame and the low thermal conductivity of the material of said retainer prevent the temperature of said frame from being transmitted to the trim 24. It is noted that only the ribs 40, 52 or 62 and the area therebetween .of each retainer engage the outer frame flange 28, 31 or 34 and that the remainder of the retainer is spaced from the frame. When the insulating strip is rectangular, as shown by the numeral 65 in FIGS. 4 and 7, the outer flange or flange portion of the frame need not project outwardly thereof since said strip does not engage upon said flange or flange portion. Even though the outer flange 50 of the retainer 48 rests on the sill member 20 and one or more of the other outer retainer flanges may engage the structural members forming the interior margin or portion of the opening 15 in the inner wall, these members are not exposed to the outdoor weather nor directly to the indoor temperature and humidity and, like the material of the retainers, have low thermal conductivity.

The insulating strip 42, 55 or 65 coacts with the ribs 40, 52 or 62 of each retainer to space the retainer from the frame 11 and ensure minimum contact and heat transfer therebetween. Normally, moisture condenses primarily on the inner frame flange 27, 30 or 33 since said flange is exposed directly to the indoor temperature and humidity as well as to outdoor weather conditions due to the high thermal conductivity of metal. Therefore, it is important to insulate in addition to spacing the inner frame flange from contact with the interior trim 24 or other interior portion of the inner wall surrounding the opening 15. Due to the low thermal conductivity of the material of the insulating strip and the minimum contact area between each retainer and outer frame flange, the retainer may be formed of material having relatively low insulating qualities. It is pointed out, however, that the thermal conductivity of the retainer material is suflicient to permit the utilization of the dead air space 47, 53 or 63 for insulating purposes whereby the insulating strip may be of minimum area and need not even be coextensive with the area of the outer frame flange. Any moisture which condenses on the interior side of the frame is confined to the dead air spaces surrounding said frame and to portions of said frame which are insulated or spaced from the interior trim or other interior wall portion sufficient to prevent the conduction of moisture to said trim or wall portion. It is noted that the insulator 10 is not limited to use with the illustrated frame, which may be circular or triangular or of other configuration, and that said insulator may be continuous or of one-piece construction when the materials of its retainer and insulating strip have sufficient elasticity.

The foregoing description of the invention is explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction may be made, within the scope of the appended claims, without departing from the spirit of the invention.

What I claim and desire to secure by Letters Patent is:

1. A thermal insulator for a metal door or window frame having interior and exterior sides exposed to indoor and outdoor or opposed temperature and humidity conditions with an upright flange extending perimetrically of and projecting transversely from its interior side including an angular retainer of low thermally conductive material mounted on the flange between the frame and the interior surface of the contiguous margin of the wall opening in which the frame is mounted so as to prevent said frame from contacting said contiguous margin, the retainer being generally U-shaped in cross-section and having a pair of flanges connected by a web, means projecting inwardly from the outer portion of one of the flanges of the retainer toward the other of said retainer flanges to engage and confine at least the outer portion of the frame flange for detachably connecting said retainer thereto with the web and said other flange of said retainer in spaced relation to the frame, and a separate strip of thermal insulating material having appreciably lower thermal conductivity than the material of said retainer confined between said retainer web and the frame flange, whereby moisture which condenses on the interior of said frame due to the differential between indoor and outdoor or opposed temperature and humidity conditions is prevented from being conducted to the interior surface of the contiguous margin of the wall opening.

2. A thermal insulator as set forth in claim 1 wherein the strip of thermal insulating material is of less width than the web of the retainer and is spaced from said one of the flanges of said retainer to provide a dead air insulating space between the frame and retainer.

3. A thermal insulator as set forth in claim 1 wherein the means for engaging and confining at least the outer portion of the flange of the frame on which the retainer is mounted includes a pair of closely spaced projections extending longitudinally of the outer portion of said one of the flanges of the retainer.

4. A thermal insulator as set forth in claim 1 wherein said other flange of the retainer engages the strip of thermal insulating material to confine said strip against displacement.

5. A thermal insulator as set forth in claim 4 including means projecting inwardly from the web of the retainer for engaging and confining the strip of thermal insulating material against displacement in coaction with said other flange of said retainer.

6. A thermal insulator as set forth in claim 1 including means projecting inwardly from the outer portion of said other flange of the retainer toward said one of said retainer flanges for engaging and preventing displacement of the strip of insulating material.

7. A thermal insulator as set forth in claim 6 including means projecting inwardly from the web of the retainer for engaging and confining the strip of thermal insulating material against displacement in coaction with the inwardly projecting means of said other flange of said retainer.

8. A thermal insulator as set forth in claim 6 wherein said other flange of the retainer engages the strip of thermal insulating material and coacts with its inwardly projecting means to confine said strip against displacement.

9. A thermal insulator as set forth in claim 6 including means projecting inwardly from the web of the retainer for engaging and spacing the strip of thermal insulating material from contact with said web.

10. A thermal insulator as set forth in claim 6 wherein the strip of thermal insulating material is of general U- shape in cross-section and engages over at least the outer portion of the flange of the frame.

11. A thermal insulator as set forth in claim 1 including means projecting inwardly from the web of the retainer for engaging and spacing the strip of thermal insulating material from contact with said web.

12. A thermal insulator as set forth in claim 1 wherein the strip of thermal insulating material is of general U-shape in cross-section for engagement over at least the outer portion of the flange of the frame.

References Cited UNITED STATES PATENTS 3,139,702 7/1964 Wasserman 52-309 FOREIGN PATENTS 542,738 11/1955 Belgium.

DAVID J. WILLIAMOWSKY, Primary Examiner.

KENNETH DOWNEY, Examiner. 

1. A THERMAL INSULATOR FOR A METAL DOOR OR WINDOW FRAME HAVING INTERIOR AND EXTERIOR SIDES EXPOSED TO INDOOR AND OUTDOOR OR OPPOSED TEMPERATURE AND HUMIDITY CONDITIONS WITH AN UPRIGHT FLANGE EXTENDING PERIMETRICALLY OF AND PROJECTING TRANSVERSELY FROM ITS INTERIOR SIDE INCLUDING AN ANGULAR RETAINER OF LOW THERMALLY CONDUCTIVE MATERIAL MOUNTED ON THE FLANGE BETWEEN THE FRAME AND THE INTERIOR SURFACE OF THE CONTIGUOUS MARGIN OF THE WALL OPENING IN WHICH THE FRAME IS MOUNTED SO AS TO PREVENT SAID FRAME FROM CONTACTING SAID CONTIGUOUS MARGIN, THE RETAINER BEING GENERALLY U-SHAPED IN CROSS-SECTION AND HAVING A PAIR OF FLANGES CONNECTED BY A WEB MEANS PROJECTING INWARDLY FROM THE OUTER PORTION OF ONE OF THE FLANGES OF THE RETAINER TOWARD THE OTHER OF SAID RETAINER FLANGES TO ENGAGE AND CONFINE AT LEAST THE OUTER PORTION OF THE FRAME FLANGE FOR DETACHABLY CONNECTING SAID RETAINER THERETO WITH THE WEB AND SAID OTHER FLANGE OF SAID 